Breaking: Bridge Collapse in Minneapolis

My thoughts and prayers go out to the families and friends of those affected by the I35W bridge collapse across the Mississippi River. The collapse occurred shortly after 6:00PM local time. Hot Air has regular updates and posted the image at left. More than 50 people were injured and it appears that three people were killed. Rescuers are still at the scene looking for victims. It also appears that at least 50 vehicles were on the bridge at the time of the collapse.

Doug Ross has photos of what the bridge looked like before the collapse, in addition to the one here at right. It was a truss design built in 1967.

James Lileks, a Minnesota local, is on top of the story, as is Powerline.

There are a couple of possible causes a structural failure that could be at fault here. One is along the lines of the Mianus River Bridge collapse in Connecticut in 1983. Metal fatigue, precipitated by rust, may be the root cause. The other may be scour of the footings, undermining their stability (that caused a collapse in upstate NY several years back - NYS Thruway in Schoharie County) .

After the Mianus bridge collapse, state and feds got real busy in inspecting bridges and other structures for collapse potential and pin and hanger designs were reinforced (that was the design that failed in CT). After the Schoharie Creek failure, bridges were also inspected for scour and riprap added to protect footings and foundations from the scour of water.

The problem is that many states have not done a sufficient job staying on top of their infrastructure - and this may be yet another tragic reminder of what happens when you don't. Indeed, as I noted earlier today, New Jersey has been lax in inspecting dam and flood control structures around the state despite the law mandating regular inspections.

Inspectors will look at everything from soil conditions to see if scour was a problem that undermined the footings to metal fatigue, to conducting tests on the metal and concrete in the structure. When the cause is finally determined, expect to see inspections turn up problems in similar structures around the country and the safety of those bridges reassessed in light of the findings from this disaster.

UPDATE:
Captain Ed is providing running updates as he lives in Minnesota.

UPDATE:
Sadly, the death toll has gone up to six, and more than 37 injured.